1. Field of the Invention
The present invention relates to a method for checking a speech channel of base stations and a vocoder of a control station in a mobile communication system and, more particularly, to a method for checking vocoders of a control station and speech channels of all service frequencies provided by base stations through functions of general calls and test calls, to thereby check call processing and handoff functions.
2. Description of the Related Art
A mobile communication system is used for radio communications between mobile objects such as people, automobiles, ships and airplanes. The mobile communication system includes a personal communication service (PCS), digital cellular system (DCS) and digital trunked radio system (DTRS). This mobile communication system consists of an operation station 10, a control station 20 and a base station 30, as shown in FIG. 1. The operation station 10 operates and maintains the control station 20 and base station 30 and gathers information, and an operator controls the control station, base station and their subsidiary apparatuses through commands provided by the operation station 10. The control station 20, located between the base station 30 and a switching center (not shown), performs functions of conversion of packet data and PCM data, transmission/reception of converted voice information, supporting handoff, power control and so on using a vocoder (not shown) corresponding to a speech channel when a call is established. Plural base stations 30 are distributed in many areas to provide call service, each consisting of a plurality of devices and channel cards in order to establish and maintain calls to a mobile station (not shown). The channel card consists of a pilot channel, synchronization channel, access channel, paging channel and speech channel according to functions.
Since the plural base stations 30 are distributed in multiple areas, the operation station 10 cannot check if all the base stations can actually provide call services with all of their service frequencies within a short period of time. To check if the vocoder of the control station 20 and all of the speech channels of the base stations are in the normal states, it is required to set calls manually. Further, the number of calls assigned to the vocoder and speech channels and causes of call cancellation can be grasped only through analysis of statistical data.
The mobile station selects a service frequency which can be provided thereto through a hash function with the number of frequencies provided by the base station 30 and phone number thereof. As long as the number of frequencies provided by the base station 30 is not changed, the mobile station sets up a call only with the frequency selected by itself. Thus, call setup is uniformly carried out by frequencies provided by the base station 30. A method of detecting a poor speech channel using a test call of a mobile communication system in order to solve the above-described problems is disclosed in Korea Pat. Appl. No. 98-22764, Jun. 17, 1998, entitled xe2x80x9cMethod of detecting poor speech channel using test call of mobile communication systemxe2x80x9d.
This method is to set up a test call to the mobile station located in each base station to check if call service is available. Here, the mobile station has access only at its service frequency because its phone number is fixed. Accordingly, this method has a problem that the call service cannot be checked with all the frequencies provided by the base station 30. In addition, in case where the test call is Markov call, the method cannot test handoff function constructed of transmission and reception of messages between the control station and the vocoder, and the base station and its speech channel, and general call processing because handoff is not supported. Moreover, the call test cannot be carried out for specific plural vocoders of the control station 20 and specific multiple speech channels of the base station 30, which are considered as poor channels. Furthermore, the vocoder of the control station 20 cannot be maintained and checked because the call test is performed only for the base station 30.
It is, therefore, an object of the present invention to provide a method for checking a speech channel of a base station and a vocoder of a control station in a mobile communication system, which checks vocoders of the control station and speech channels of all service frequencies provided by the base stations through functions of general calls and test calls, to thereby check call processing and handoff functions, maintaining high quality call services.
To accomplish the object of the present invention, there is provided a method for checking a speech channel of a base station and a vocoder of a control station in a mobile communication system, the method is characterized in that, when an operation station requests of a mobile station that a call is established with a specific frequency provide by the base station, the base station transmits a call assignment message to the mobile station in idle state to set up a call with a frequency designated by the operation station, and the base station also sends a call setup message to the mobile station or the operation station transmits a message to the mobile station, to thereby support the basic incoming call/outgoing call, incoming/outgoing Markov calls and incoming/outgoing loop back calls. Accordingly, it is possible to check if the mobile station can establish a call with all frequencies provided by the base station without regard to the number of service frequencies of the base station and the phone number of the mobile station.
Furthermore, the method for checking a speech channel of a base station and a vocoder of a control station in a mobile communication system can check the flow of a series of messages related with general incoming/outgoing calls between the base station and control station and between the vocoder and speech channel, and supports handoff in case of the loop back call or general incoming/outgoing calls to enable handoff function test when the mobile station requests handoff.